(1) Field of the Invention
The present invention relates to a quick extraction kit and a method utilizing the quick extraction kit, and more particularly relates to a quick extraction kit adapted to a procedure of detecting pesticide residues in agricultural products and a method utilizing the quick extraction kit.
(2) Description of the Prior Art
It has been widespread to apply pesticides on crops for discouraging the pests to increase agricultural production. Based on food safety requirements, all countries in the world have set standards for pesticide residue testing to establish Maximum Residue Limits (MRL).
For determination of pesticide residues in fruits, vegetables, grains, dried beans, tea, spice and other herbaceous plants, an existing detection method is sampling, and then pre-treating the sample by the QuEChERS method (Quick, Easy, Cheap, Effective, Rugged, Safe) to get a primary test liquid which is dewatered and purified. Next, the primary test liquid is processed to form a test liquid suitable for being detected in instruments. The test liquid is detected by liquid chromatograph/tandem mass spectrometer or gas chromatograph/tandem mass spectrometer, and finally, data of the detected result of said instruments is processed to obtain a result of pesticide residues detection.
It takes much time for sample pretreatment by the method above. The QuEChERS method needs to carry out following steps:
Granulating the sample by a blender to obtain a homogenized sample for increasing contact area of the sample;
Weighing proper quantity of the sample, such as 10 gram;
Adding an extraction solvent, such as acetonitrile solution, into the homogenized sample, then strongly shaking the homogenized sample with the extraction solvent for a period of time to form an extraction liquid, the ratio of the homogenized sample and the extraction solvent is 1:1 in weight and volume, for example, each 10 gram sample need to be added 10 ml acetonitrile solution;
Adding proper quantity of a mixture buffer agent, such as 6.5 gram, into the extraction liquid, wherein the mixture buffer agent has components comprising 4 gram anhydrous magnesium sulfate, 1 gram sodium chloride, 1 gram trisodium citrate and 0.5 gram disodium hydrogen citrate;
Strongly shaking the extraction liquid added the mixture buffer agent for a period of time by a homogenizer (SPEX SamplePrep 2010 GenoGrinder®), then centrifuging the extraction liquid added the mixture buffer agent to make the extraction liquid stratified by a centrifuge;
Taking proper quantity of a supernatant of the extraction liquid, such as 6 ml; and
Based on the type of the sample, adding different adsorbents into the supernatant.
For example, when the sample is fruit, vegetable or crop, the adsorbent is a mixture of 150 mg primary secondary amine (PSA) and 900 mg anhydrous magnesium sulfate; if the sample is tea, the adsorbent is a mixture of 450 mg PSA and 900 mg anhydrous magnesium sulfate; if the sample comprises carotenoid, the adsorbent is a mixture of 150 mg PSA, 855 mg anhydrous magnesium sulfate and 15 mg graphitized carbon black (GCB). Besides, if the sample contains high quantity of chlorophyll, the adsorbent is a mixture of 150 mg PSA, 855 mg anhydrous magnesium sulfate and 45 mg GCB.
Afterward, the supernatant added the adsorbent is strongly shaken for a period of time by the homogenizer and then centrifuged by the centrifuge to obtain a centrifugal liquid for a primary test liquid.
The primary test liquid still should be treated by some steps to become the test liquid which is capable of being detected by instruments. For example, the primary test liquid is separately treated by a step of air drying, a step of adding methanol, acetone or hexane, a step of adding formic acid and a step of filtering by a filter membrane in sequence.
It takes about two hours to obtain the required primary test liquid from the sample by the QuEChERS method which would slow down the speed of the procedure of detecting pesticide residues and be impossible to quickly take the result of detecting pesticide residues. In view of this, it is important to provide an easier and faster method to obtain the required primary test liquid from the sample and solve said problem.
A solid phase extraction column to obtain a primary test liquid from a sample has been disclosed in the patent of CN103111091. However, the sample should be treated in the processes of shaking, twice-centrifuging, water-bathing and rotary evaporating to obtain a concentrated solution. The solid phase extraction column also needs to be treated by adding anhydrous sodium sulfate first and washing with acetonitrile/methyl benzene. Then, the concentrated solution is added into the treated solid phase extraction column to obtain the primary test liquid. Although the solid phase extraction column of said patent is filled in two layers of different materials (the upper layer consists of amino Silica NH2 and amide-modified polyethylene divinylbenzene, the bottom layer consists of graphite carbon), it still need much time for treating the sample and the solid phase extraction column to obtain the primary test liquid from the sample by the solid phase extraction column.
A solid phase extraction column has been disclosed in the patent of CN202631493, the solid phase extraction column is filled by three layers which are PSA, HBL and GCB. Because of these three layers all are absorbents, if the solid phase extraction column is used in the QuEChERS method mentioned above, the sample still needs the treatments of adding the mixture buffer agent, shaking and centrifuging after adding the extraction solvent. The primary test liquid then is obtained from the sample by the solid phase extraction column.
A similar technique has been disclosed in the patent of CN103055540. This patent has disclosed a purified column which is filled by a monolayer adsorbing filter. The adsorbing filter is a filter mixture of N-propyl ethylenediamine and anhydrous magnesium sulfate, a filter mixture of multi-walled carbon nanotubes and anhydrous magnesium sulfate, or a filter mixture of PSA, anhydrous magnesium sulfate, multi-walled carbon nanotubes and GCB. These filter mixtures are used for absorbents. Like the patent of CN202631493, even utilizing the purified column in the QuEChERS method, it also takes much time to obtain the primary test liquid for the sample treated by adding a mixture buffer agent, shaking and centrifuging.
Besides, the patent of U.S. Pat. No. 6,541,273 has disclosed a solid phase extraction cartridge filled in multi-layer absorbents, but it still spends much time to centrifuge a sample before obtaining a primary test liquid.
From the above description, obviously, it is impossible to quickly obtain the result of detection by the QuEChERS method, which spends too much time to obtain the primary test liquid. However, this problem is obviously unable to be solved by the solid phase extraction column of the prior art.